linux-kernel - Re: NFS hang + umount -f: better behaviour requested.

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Date:	Fri, 24 Aug 2007 11:09:14 -0400
From:	Ric Wheeler <ric@....com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
CC:	John Stoffel <john@...ffel.org>,
	Peter Staubach <staubach@...hat.com>,
	Robin Lee Powell <rlpowell@...italkingdom.org>,
	linux-kernel@...r.kernel.org
Subject: Re: NFS hang + umount -f: better behaviour requested.

J. Bruce Fields wrote:
> On Tue, Aug 21, 2007 at 02:50:42PM -0400, John Stoffel wrote:
>   
>> Not in my experience.  We use NetApps as our backing NFS servers, so
>> maybe my experience isn't totally relevant.  But with a mix of Linux
>> and Solaris clients, we've never had problems with soft,intr on our
>> NFS clients.
>>
>> We also don't see file corruption, mysterious executables failing to
>> run, etc.  
>>
>> Now maybe those issues are raised when you have a Linux NFS server
>> with Solaris clients.  But in my book, reliable NFS servers are key,
>> and if they are reliable, 'soft,intr' works just fine.
>>     
>
> The NFS server alone can't prevent the problems Peter Staubach refers
> to.  Their frequency also depends on the network and the way you're
> using the filesystem.  (A sufficiently paranoid application accessing
> the filesystem could function correctly despite the problems caused by
> soft mounts, but the degree of paranoia required probably isn't common.)
>   
Would it be sufficient to insure that that application always issues an 
fsync() before closing any recently written/updated file? Is there some 
other subtle paranoid techniques that should be used?

ric

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